Key points
- St. Louis encephalitis virus spreads to people through the bite of an infected mosquito.
- Symptoms include fever, headache, nausea, vomiting, and tiredness.
- No vaccines or medicines are available to prevent or treat St. Louis encephalitis.
- You can reduce your risk by taking steps to avoid mosquito bites.
Overview
St. Louis encephalitis is a disease caused by a virus spread by infected mosquitoes. The annual number of St. Louis encephalitis cases varies widely. Most cases in the United States occur in Eastern and Central states, but sporadic cases and outbreaks have occurred in the Southwest.
Symptoms
Most people infected with St. Louis encephalitis virus do not have symptoms. People who do become ill may experience fever, headache, nausea, vomiting, and tiredness.
Some people may develop severe neuroinvasive disease, such as encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes that surround the brain and spinal cord).
How it spreads
St. Louis encephalitis virus spreads to people through the bites of infected mosquitoes.
Prevention
No vaccines or medicines are available to prevent St. Louis encephalitis. Reduce your risk of infection by preventing mosquito bites.
Testing and diagnosis
See your healthcare provider if you have symptoms after being exposed to mosquitoes in an area where St. Louis encephalitis virus spreads.
Treatment
No medicines are available to treat St. Louis encephalitis. Antibiotics do not treat viruses. Rest, fluids, and over-the-counter pain medications may relieve some symptoms. In severe cases, patients often need to be hospitalized to receive supportive treatment, such as intravenous fluids, pain medication, and nursing care.
For healthcare providers: Treatment and Prevention of St. Louis Encephalitis